This proposal was stimulated by the NIMH program on two-dimensional electrophoresis. A high resolution gel system will be developed for the analysis of small peptides in complex mixtures. The first dimension will utilize isoelectric focusing, containing immobile ampholites, glyoxylagarose, 6M guanidine HCl, and a fractionated triton X-100. The second dimension uses molecular weight separation with a linear pore gradient gel and cationic surfactant sodium cholate (SC), which forms a smaller micelle than SDS. The critical micelle concentration with SC is higher and easier to remove by washing. Detection of the peptides will use an ultra sensitive silver strain, which is a modification of Merril's method. The fixation step, formerly done in a high concentration of acetic acid and alcohol will be changed to 1:1% aqueous glutaraldehyde. The above system will be distributed as laboratory trial kits as soon as kits become available. It is anticipated that they will be utilized for both biomedical research and in clinical diagnostic applications, as in the analysis of hormonal peptides in human spinal fluid or in blood. (3)